1. Field of the Invention
This invention relates to a liquid ejection recording apparatus for ejecting flying droplets to a recording medium and recording character images or the like thereon and to a liquid ejection recording head used in such apparatus, and more particularly, to a liquid ejection recording head suitable for being removably mounted on a carriage scanning relative to the recording medium and to a liquid ejection recording apparatus in which a driving voltage for driving the liquid ejection recording head is adjustable for each liquid ejection recording head.
2. Description of the Prior Art
The non-impact recording methods have recently drawn attention in that the occurrence of noise during the recording is negligibly small. Among them, the ink jet recording method (the liquid ejection recording method) which is capable of accomplishing high-speed recording and moreover, can accomplish full color printing without requiring a special process of fixation for recording on plain paper is a very effective recording method, and various types of such recording method have heretofore been proposed and some of them have already put into commercial use and some of them are still being studied.
Such liquid ejection recording method effects the recording by causing droplets of recording liquid called ink to fly and adhere to a recording medium, and may be divided broadly into several types by the method of forming the droplets of the recording liquid and the method of controlling the direction of flight of the formed droplets.
Among them, the liquid ejection recording methods disclosed, for example, in U.S. Pat. No. 3,683, 212, U.S. Pat. No. 3,747,120 and U.S. Pat. No. 3,946,398 are the so-called drop-on-demand recording method in which droplets are discharged from discharge orifices in accordance with a recording signal and these droplets are caused to adhere to the surface of a recording medium to thereby accomplish the recording. In this recording method, only the droplets necessary for the recording are discharged and therefore, it is not necessary to install any special means for recovering or treating the discharged liquid un-necessary for the recording and thus, the apparatus itself can be made simple and compact and nowadays, this recording method particularly attracts attention due to the fact that it is unnecessary to control the direction of flight of droplets discharged from discharge orifices and the fact that multi-color recording can be accomplished easily.
A liquid ejection recording method entirely different from the above-described liquid ejection recording method in the principle of formation of flying droplets is disclosed in Japanese Laid-Open Patent Application No. 51837/1979. This liquid ejection recording method is not only very effectively applicable to said drop-on-demand recording method, but also can easily realize a highly dense multi-orifice recording head, and therefore, it has a feature that recorded images of high resolution and high quality can be obtained at a high speed.
The liquid ejection recording apparatus used in these drop-on-demand recording methods is usually of a structure having a recording head comprised of discharge ports (orifices) for discharging droplets, liquid flow paths communicating with the orifices and having energy generating elements for forming flying droplets, and a liquid chamber communicating with the liquid flow paths and storing therein liquid to be supplied to these flow paths.
However, in the liquid ejection recording apparatus having the construction as described above, the optimum driving voltages inherent to the liquid ejection recording heads thereof are different and irregular, and therefore, it is necessary to adjust a driving voltage generating circuit in the liquid ejection recording apparatus in accordance with the optimum driving voltage inherent to the liquid ejection recording head.
If this adjustment is neglected, the following problem will arise. That is, when a liquid ejection recording head whose inherent voltage is higher than the driving voltage supplied from the driving voltage generating circuit of the liquid ejection recording apparatus is mounted on the recording apparatus, stable flying droplets cannot be obtained or, in the worst case, droplets cannot be discharged. Conversely, when a liquid ejection recording head whose inherent voltage is lower than the driving voltage supplied from the driving voltage generating circuit of the liquid ejection recording apparatus is mounted on the recording apparatus, unnecessary droplets, called satellities, are secondarily ejected or an excessively great load is applied to the energy generating elements to remarkably reduce their service life, and in the worst case, the energy generating elements may be destroyed.
Accordingly, when the liquid ejection recording head is to be interchanged by reason of trouble with it or the like, a high-degree of maintenance work which requires a part of the driving voltage generating circuit to be changed becomes necessary, and this has led to a problem that the manufacturer must make expensive liquid ejection recording heads whose trouble rate is very low.
In fact, in the liquid ejection recording apparatus of this type, the liquid ejection recording head (hereinafter referred to simply as the head) has often been interchanged from the viewpoint of securing the reliability of the head. However, each head has its inherent optimum driving voltage and the value of that voltage differs from head to head, and therefore, it has been necessary to adjust the driving voltage generating circuit in the liquid ejection recording apparatus in accordance with the optimum driving voltage value of the head.
Thus, each manufacturer has shown the optimum driving voltage value by directly writing the voltage value on the head or by sticking, on the head, a label on which the optimum driving voltage value is written.
Therefore, when actually interchanging the head, a cumbersome procedure wherein, according to the voltage value written or stuck on the head, the operator such as the user or serviceman most adjust the driving voltage generating circuit on the basis of a corresponding table, or the like, which must be resorted to. Also, the voltage value directly written on the head is apt to fade away during the transportation or the label stuck on the head may peel off during transportation, and this has led to the occurrence of a trouble that the driving voltage value becomes unknown.